Various compounds can have different crystal structures depending on factors such as temperature. For example, chocolate, and more particularly cocoa butter within chocolate, can generally have one of six crystal structures depending on how it is produced. The crystal structures range from type I to type VI with each crystal type having a different melting point. Generally accepted melting points of cocoa butter crystal types are as follows: type I: 17° C.; type II: 21° C.; type III: 26° C.; type IV: 28° C.; type V: 34° C.; type VI: 36° C. Type VI crystals require an extended duration of time (a matter of months) to form and are not found in typical chocolate.
Tempering of chocolate during production is necessary to produce a product with as many type V crystals as possible, which is the cocoa butter crystal structure typically used for consumer chocolate. To temper chocolate to produce type V crystals, the chocolate can be heated to a temperature which is higher than the type IV crystal melting temperature, for example 31° C. to 32° C. for a duration of time which is sufficient to melt the type I to type IV crystals, then cooled. During the cooling, the type V crystals that remain function as crystallization nuclei, around which other type V crystals will form.
In another method of forming type V cocoa butter crystals, a solid seed chocolate having a preponderance of type V crystal structures is dispensed into a melted chocolate which is at a temperature between the type IV and type V crystal melting point. The type V crystals in the solid chocolate function as crystallization nuclei for the molten material such that the melted chocolate crystallizes into a type V cocoa butter crystal structure.
Quality chocolate with a type V crystal structure has desirable characteristics, such as a shiny surface, a firm texture, a good snap, a melting point which is above typical ambient temperatures but generally around human body temperature and a texture and appearance which will not degrade over time.
Attempts have been made to fashion three dimensional designs with chocolate using a chocolate dispenser (printer) with a controlled placement of material. However, chocolate must be heated above the type VI crystal structure melting point so that the chocolate flows with sufficient ease for printing, while heating chocolate to this printing temperature can cause the chocolate to lose temper. Thus current 3D chocolate printers result in 3D structures which do not have a high percentage of cocoa butter type V crystal structures. Current methods of chocolate printing can result in printed chocolates that lack the required resistance to elevated temperatures and other desirable properties of snap, surface finish, and texture.